It is thought some of the investigators could be offered roles in public protection.

Public protection is the only department expanding its workforce, following the child sexual exploitation scandal in Rotherham, where a report suggested 1,400 children had been abused by largely Pakistani-heritage men over a 16-year period while authorities turned a blind eye because of sensitivities over the ethnicity of offenders.

But Mr Armitage, who was a police community support officer before he was appointed as a union official, said by the end of the latest round of spending cuts he expects South Yorkshire Police chiefs to have shed a third of the force’s civilian workers.

He said: “Civilian investigators review CCTV, take statements, put case files together and do witness liaison work – they are invaluable to those working on major incidents, so it is worrying to wonder how that work is going to be done in the future when people already have their own jobs to do. Our fear is police officers will have to come off the frontline to pick up the pieces.

He said he fears for the future of the county’s police service with officer and staff numbers continuing to fall.

Mr Armitage said: “If they carry on culling like they are we will get to the point of no return and it will be the people of South Yorkshire who suffer.

“Morale is at rock bottom. Police officers are protected from redundancy, it is police staff taking the brunt of these cuts.”

A South Yorkshire Police spokeswoman said: “There are presently 28 district-based civilian investigator roles. All will be removed as part of the district review.

“There has been a review and redesign of structures and processes which will see this function absorbed into inspector-led flexible local policing teams.

“Service to the public and our business community will not reduce. We will seek to concentrate resources where they are required.

“In terms of savings, this contributes to the overall £8.1 million local policing review savings target.

“The decision to reduce investigator roles was not taken lightly. The force is faced with funding challenges as a result of budget reductions. With the growth of public protection, it may be opportunities are available for district staff to redeploy into this field, an option we are exploring.”